McAfee Secure sites help keep you safe from identity theft, credit card fraud, spyware, spam, viruses and online scams
Business Home → McAfee Labs → Threat Intelligence

Downloader-YN

This page shows details and results of our analysis on the malware Downloader-YN

Threat Detail

Malware Type: Trojan

Malware Sub-type: Downloader

Discovery Date: 2005-04-19

Next Steps:

Overview

This is a trojan detection. Unlike viruses, trojans do not self-replicate. They are spread manually, often under the premise that they are beneficial or wanted. The most common installation methods involve system or security exploitation, and unsuspecting users manually executing unknown programs. Distribution channels include email, malicious or hacked web pages, Internet Relay Chat (IRC), peer-to-peer networks, etc.


Minimum DAT

4472 (2005-04-19)

Updated DAT

4892 (2006-11-09)

 Minimum Engine

5.1.00

File Length

Varies

 Description Added

2005-04-19

Description Modified

2005-08-30

Malware Proliferation

Characteristics

This is a downloader trojan that is written in MSVC.  There are several variants of the trojan exist.  Newer variants require the latest DATs for detection and cleaning.

When run, the trojan creates registry run key to load itself at Windows startup:

  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    (trojan file name) = (trojan file path)

It registers itself as a local server using a randomly generated CLSID:

  • HKEY_CLASSES_ROOT\CLSID\{random CLSID}\LocalServer "
    (Default)" = (trojan file path)

The trojan downloads/executes additional trojan/adware from a specific website.

The trojan also displays the following message box periodically:

Once clicked "yes", it opens an advertising web site using IE.

Symptoms

  • Existence of registry keys/files mentioned above
  • Pop-up dialog box displayed.

Method of Infection

N/A. Downloaders are not viruses, and as such do not themselves contain any method to replicate. However they may themselves be downloaded by other viruses and/or Trojans to be installed on the user's system.

Many of these additionally are mass spammed by the author to entice people into double-clicking on them.

Alternatively they may be installed by visiting a malicious web page (either by clicking on a link, or by the website hosting a scripted exploit which installs the Downloader onto the user's system with no user interaction.

Removal

All Users:
Use current engine and DAT files for detection and removal.

Modifications made to the system Registry and/or INI files for the purposes of hooking system startup, will be successfully removed if cleaning with the recommended engine and DAT combination (or higher).

But in some particular cases, the following steps need to be taken.

Please go to the Microsoft Recovery Console and restore a clean MBR.

On Windows XP:

  • Insert the Windows XP CD into the CD-ROM drive and restart the computer.
  • When the "Welcome to Setup" screen appears, press R to start the Recovery Console.
  • Select the Windows installation that is compromised and provide the administrator password.
  • Issue 'fixmbr' command to restore the Master Boot Record
  • Follow onscreen instructions.
  • Reset and remove the CD from CD-ROM drive.


On Windows Vista and 7:

  • Insert the Windows CD into the CD-ROM drive and restart the computer.
  • Click on "Repair Your Computer".
  • When the System Recovery Options dialog comes up, choose the Command Prompt.
  • Issue 'bootrec /fixmbr' command to restore the Master Boot Record.
  • Follow onscreen instructions.
  • Reset and remove the CD from CD-ROM drive.

Variants

United States - English